A variety of industries utilize pipes formed from thermoplastic materials including, but not limited to, polyethylene, polypropylene and PVC. Joints between sections of such plastic pipes may be formed by inserting the spigot end of one pipe into the bell socket end of a second pipe. Such socket and spigot pipe joints between plastic pipes are well known in the art. For example, U.S. Pat. No. 3,539,205 discloses a pipe joint including a plastic pipe with a bell end portion further having an annular gasket seat portion for containing an annular gasket. The spigot end portion of another pipe is inserted into the bell end portion and through the annular gasket wherein the annular gasket forms a seal between the bell end portion and the spigot end portion.
The use of a gasket not only improves the seal of the pipe joint, but also allows either a restrained or unrestrained pipe joint depending on the particular type of gaskets used. The formation of a thermoplastic pipe with a bell socket end containing a gasket cavity, however, typically requires the use of expensive machinery, such as expandable mandrels, to achieve the differential internal diameters of the bell socket. Further, corrosion of restraining gaskets placed within the gasket cavity may reduce the shelf life of such pipes. Therefore, a need exists for a less expensive systems and methods for the production of thermoplastic pipes, which contain not only a bell socket end, but also a gasket cavity containing a toothed restraining gasket.